1. Field of the Invention
The present invention relates generally to an apparatus for automatic mounting of circuit components on a printed circuit board and, more particularly, to an apparatus for supplying components to a printed circuit board equipping head.
2. Description of the Related Art
The equipping of printed circuit boards with electrical or electronic components is carried out either manually or through the use of automatic equipping units. In all equipping processes, even those using wired components, the individual component is prepared in a separate work step before the subsequent circuit board equipping step. The wired components then have their wires, or leads, plugged into bores in the printed circuit board which are provided for the components. When mounting non-wired components, such as SMD (surface mount device) components, on the printed circuit boards, the individual components are pressed in the correct position onto group points or into solder paste. The application of the group points or of the solder paste to the circuit board has been performed in a previous work step.
Given the mounting of wired components onto the circuit boards, the leads or wires of the component project through the bores in the circuit board and beyond the underside of the circuit board and are usually cut to a functionally proper length after the end of the equipping process. The components are prevented from falling out of the printed circuit board by bending of the leads over at the back side of the circuit board.
In known apparatus for equipping printed circuit boards, the component is picked up from a component processing and testing location by an equipping head and is centered in a correct position in the equipping head for a subsequent equipping event. When the printed circuit boards are equipped with SMD components, an X/Y coordinate table is usually used to position the component held in the equipping head over the prescribed equipping position on a stationarily positioned printed circuit board. In an apparatus for equipping circuit boards with wired components which require a tool mounted below the table (a so-called under table tool) for cutting the wires, or leads, to length and bending the portions of the leads extending through the circuit board, the printed circuit board is moved under a stationarily positioned equipping head by a compound table that is displaceable in the X and Y directions. In both instances, the equipping event is then carried out by lowering the equipping head so that the component is exactly positioned on the printed circuit board. In some automatic equipping units using robotic technology, the equipping head and the under table tool are moved into the equipping position on a removably arranged printed circuit board.
One disadvantage of the automatic equipping units which have previously been present in the marketplace is the serial execution of the component preparation, in the component testing, in the grasping of the components, and in the equipping of the components on the circuit boards. This serial execution is a result of using only one equipping head per machine.
Apparatus are also known which include multiple equipping heads provided on a turret head, the turret head being secured to an X/Y coordinate drive. The length of time required for the serial equipping event can ben greatly reduced with this known apparatus by performing a component collecting motion and a subsequent component equipping function of the multiple equipping head. The spectrum of components which can be processed with such an apparatus, however, is greatly restricted due to the special limitation of the positioning system with reference to an equipping position of the components on the circuit board. The use of under table tools required for equipping a printed circuit board with wired components is not functionally possible in the known multiple equipping head apparatus.
All known automatic equipping units involve special solutions adapted to specific types of components. A multitude of different automatic equipping units is consequently required for mounting the entire spectrum of electrical and electronic components. The different automatic equipping units have completely different basic structures. The equipping, or component mounting, times for the automatic equipping units usually is approximately several seconds per component when the time required for changing the printed circuit boards is included in the equipping sequence.